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this all about mycotoxin


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A mycotoxin is a toxic secondary metabolite produced by organisms of the fungus kingdom, commonly known as molds. The term ‘ mycotoxin ’ is usually reserved for the toxic chemical products produced by fungi that readily colonize crops

Information About Fungus:

Information About Fungus Range from single cells to fruiting bodies that form molds, mushrooms, smuts, and yeasts. Absorb nutrients from living or deceased organisms, contain no chlorophyll. If multicellular , they have tubular filaments called hyphae that branch out. Reproduce using spores.

What is a Mycotoxin?:

What is a Mycotoxin ? Secondary metabolites of a fungus that produce toxic results in another organism. Cytotoxic: disrupt cell structures such as membranes, and processes such as protein, DNA, and RNA synthesis. Lack of visible appearance of fungus does not negate presence of mycotoxins. Toxins can remain in the organism after fungus has been removed. Less selective in organism selection, can cross plant species barrier. Can be heat stable, not destroyed by canning or other processes.

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Present major problems for clinicians. Diseases produced by mycotoxins are difficult to diagnose. Why so ? Very few mycotoxins produce overt signs of poisoning or other symptoms Why ? They are bizarre molecules with molecular weight 50 - >500. Such small molecules induce no response in human immune system ! Major danger of mycotoxin in diet is our inability to detect them biologically.

the concept of Mycotoxins?:

the concept of Mycotoxins? An outbreak of an unknown disease killed poultry birds in 1960s This was named Turkey X disease After investigations it was finally traced to mycotoxins in groundnut meal feed imported from Brazil The feed was shown to contain a compound that could cause cancer Today we know this mycotoxin by the name of AFLATOXIN – A CLASS I CARCINOGEN

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Fungi Substrate Mycotoxin Aspergillus flavus Maize, groundnut, oilseed, cotton seed Aflatoxin Aspergillus parasiticus Maize, groundnut, oilseed, cotton seed Aflatoxin Aspergillus nomius Maize, groundnut, oilseed, cotton seed Aflatoxin Aspergillus ochraceus Barkey wheat Ochratoxin Aspergillus carbonerius Grapes wine coffee Ochratoxin Fusarium oxysporum Wheat barley maize Fumonisins Fusarium sp. Wheat barley maize T-2 toxin Penicillium verrucosum Wheat barley maize Ochratoxin Claviceps purpurea Rye Ergot alkaloids Stachybotrys hay satratoxins

Mycotoxicosis Severity:

Mycotoxicosis Severity Type of mycotoxin . Exposure duration and dose. Age. Nutritional status and health of individual. Synergistic effect with other chemicals or mycotoxins . Primary target organs. • liver, lungs, kidney, and nervous, endocrine, immune systems

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Factors affecting mold growth and mycotoxin production in creral grains Intrinsic factors Extrinsic factors Ingredient composition(lipids, CHO, trace metals,etc . Relative humidity: RH greater than 70% favors fungal growth pH: Fungal growth decrease with decreasing pH Environmental temperature: the optimal temprature for fungal growth and mycotoxin production varies with the spices. Grain moisture: optimal grain moisture is >13% for saprophytic and >20% for phytopathogenic fungi O 2 /CO 2 : Fungi are aerobic organisms. Studies with mycotoxigenic Fusaria showed that in storage atmosphere containing 5% O2 and 40% CO2, fungi growth affected and no mycotoxin are produced Water activity (aw): this parameter is related to the water that is actually available for fungi growth Surface area of grain: smaller particles have increased surface area which predisposes mold growth Adapted from Lesson et al. 2001

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Mycotoxins Mycotoxins may be: Carsinogenic : Aflatoxin B1, Ochratoxin Nephrotoxic : Ochratoxin , Citrinin Nerotoxic : Fumonsin B1 Estrogenic : Zearalenone Dermonecrotic : Thricothecens

What is Aflatoxin??:

What is Aflatoxin?? Aflatoxin is the name for a group of toxins (poisonous chemical compounds) that are produced by two fungi called Aspergillus flavus and Aspergillus parasiticus .

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Aflatoxin Aflatoxin is the mycotoxin of greatest concern in feeding of poultry both outright toxic and carcinogenic liver ( hepatoma ) and blood clotting problems traditionally, sources include corn, cottonseed and peanuts aflatoxin contamination varies year to year Aflatoxins (moldy feed) inhibit microbial intestinal synthesis

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Aflatoxin is produced by Aspergillus flavus and A. parasiticus Aflatoxins occur in different chemical forms; B1,B2, G1, G2, and M1. The allowable toxin limits are 20 ppb in nuts . Allowable limit in meats, corn, and wheat is also 0.5 ppb. The acute lethal dose for adult human is thought to be 10–20 mg. The primary target organ for aflatoxin is the liver.. Aflatoxin causes gross liver damage, resulting in liver cancer ( hepatocarcinogen ). It can also cause colon and lung cancer. classified aflatoxin B1 as a group I carcinogen . Required humidity > 14% temperature > 25°C High melting point i.e. 250°C

Mouldy feed in sacks:

Mouldy feed in sacks Boatful of moldy feed

Aspergillus Life Cycle:

Aspergillus Life Cycle

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First of mycotoxins to be investigated in aquaculture first report – trout hatcheries in 1960s The carcinogenic effect of aflatoxin B1 has been studied in fishes salmonid , rainbow trout, channel catfish, Nile tilapia, guppy and Indian major carps and Penaeus monodon .

Pathology of aflatoxicosis:

Pathology of aflatoxicosis Initial signs Pale gills Impaired blood clotting Anaemia Loss of appetite Poor growth


CLINICAL SIGNS ON PROLONGED FEEDING Yellowing of body( yellow Disease in C. catfish) Eye opacity Cataract Blindness Skin lesion Fin and tail rot Reduced no of RBC Abnormal swimming Impaired immune function(IMC)

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* During the mutagenic action, toxin binds to DNA, especially the liver mitochondrial DNA resulting in point mutation addition or substitution in DNA and affect liver function (hence hepatotoxic ). * Teratogenic action leads to birth defects * The carcinogenic effect cause irreversible defects in cell physiology resulting in abnormal cell growth and metastasis. * In recent years, the importance of mycotoxins has been highlighted for their potential use as weapon for bioterrorism.

Other Chronic Effects of Aflatoxin:

Other Chronic Effects of Aflatoxin Immunological Suppression Using animal models, AFB1 has been shown to impair normal immune function either by reducing phagocytic activity or reduce T cell number and function. Nutritional Interference Aflatoxin is shown to have a dose response relationship between exposure to aflatoxin and rate of growth among small children. In addition, it also interferes in nutrient modification such as Vitamin A or D in animal models.

why does toxicity vary in fishes?:

why does toxicity vary in fishes? The age and species of the fish. Fry are more susceptible to aflatoxicosis than adults some species of fish are more sensitive to aflatoxins than others. plant ingredients are more infested . Tropical conditions-more favourable

Liver Cell Carcinoma: aflatoxicosis:

Liver Cell Carcinoma: aflatoxicosis no outward signs of aflatoxicosis or hepatoma during the early stages of tumor growth enlargement of the liver may then take place and the fish becomes emaciated as disease progresses, liver nodules grow and contact other organs Confirmatory diagnosis via histopathology/ oncology of the tumor

Hepatoma Therapy and Control:

Hepatoma Therapy and Control there is no therapy must eliminate aflatoxin from the ration in subsequent generations by addition of proprionic acid or ammonia treatment of the feedstuff prognosis: morbidity may reach 70% in culture facilities linear relationship between cottonseed meal intake and incidence of hepatoma

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Tilpia fed with moldy feed Tilapia fed with feed without moulds

Aflatoxin B1 and Tumor Induction:

Aflatoxin B1 and Tumor Induction


Aflatoxicosis Aflatoxicosis is primarily a hepatic disease.


MAJOR GROUP Aflatoxins are a type of mycotoxin produced by Aspergillus species of fungi, such as A. flavus and A. parasiticus The umbrella term aflatoxin refers to four different types of mycotoxins produced, which are B 1 , B 2 , G 1 , and G 2 Aflatoxin B 1 , the most toxic , This is potent carcinogen and has been directly correlated to adverse health effects, such asliver cancer, in many animal species.

Ochratoxin :

Ochratoxin Ochratoxin is a mycotoxin that comes in three secondary metabolite forms, A, B, and C . All produced by Penicillium and Aspergillus species. The three forms differ in that Ochratoxin B (OTB) is a nonchlorinated form of Ochratoxin A (OTA) and that Ochratoxin C (OTC) is an ethyl ester form Ochratoxin A . Aspergillus ochraceus is found as acontaminant of a wide range commodities including beverages such as beer and wine. Aspergillus carbonarius is the main species found on vine fruit, which releases its toxin during the juice making process. [

Ergot Alkaloids:

Ergot Alkaloids Ergot Alkaloids are compounds produced as a toxic mixture of alkaloids in the sclerotia of species of Claviceps , which are common pathogens of various grass species . The ingestion of ergot sclerotia from infected cereals, commonly in the form of bread produced from contaminated flour, cause ergotism the human disease historically known as St. Anthony’s Fire . There are two forms of ergotism : gangrenous, affecting blood supply to extremities, and convulsive, affecting the central nervous system


Patulin Patulin is a toxin produced by the P. expansum , Aspergillus , Penicillium , and Paecilomyces fungal species. P. expansum is especially associated with a range of moldy fruitsand vegetables, in particular rotting apples and figs. It is destroyed by the fermentation process and so is not found in apple beverages, such as cider . Although patulin has not been shown to be carcinogenic, it has been reported to damage the immune system in animals. [21] In 2004, the European Community set limits to the concentrations of patulin in food products. They currently stand at 50 μg /kg in all fruit juice concentrations, at 25 μg /kg in solid apple products used for direct consumption, and at 10 μg /kg for children's apple products, including apple juice

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Inflammed and jaundiced fish liver Inflammed and jaundiced fish liver

Binding agents and deactivators :

Binding agents and deactivators In the feed and food industry it has become common practice to add mycotoxin binding agents such as Montmorillonite or bentonite clay in order to affectively adsorb the mycotoxins

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To reverse the adverse effects of mycotoxins , the following criteria are used to evaluate the functionality of any binding additive : Efficacy of active component verified by scientific data A low effective inclusion rate Stability over a wide pH range High capacity to adsorb high concentrations of mycotoxins High affinity to adsorb low concentrations of mycotoxins Affirmation of chemical interaction between mycotoxin and adsorbent Proven in vivo data with all major mycotoxins Non-toxic, environmentally friendly component

Prevention strategies:

Prevention strategies Good agronomic practices Selection of resistant varieties Proper crop rotation Plow up harvest residues Good storage practices Keep in dry, cool place Keep diff. ingredients separately

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Addition of mycotoxin absorbing agent Mycosorb -From glucan fraction of yeast cell wall Destroy the affected feedstuffs Different kits are available for rapid identification

Thank you:

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